1. Field of the Invention
The invention is related to the field of data compression and in particular to an on-the-fly data compression system using a word representation by associative processing buffer and content induced transaction overlap transmission protocol.
2. Prior Art
In the transmission of image information, such as the output of a television camera or similar device, data compression is a useful tool since it reduces the channel bandwidth required to transmit the data. It also finds use in the storage of large quantities of data, since it reduces the storage requirements for a given amount of data.
Various methods for data compression are known in the art. Komura et al in U.S. Pat. No. 3,801,737 describes a video signal compression and expansion system in which the binary coded video signals of one scanning line are compared, bit by bit, to the signals of the preceding line. The compression coding is accomplished with respect to a reference binary coded video signal. In an alternate system, Komura et al in U.S. Pat. No. 3,895,184 teaches a facsimile system with buffered transmission and reception in which the coded and compressed signals are temporarily stored within a storage device through a buffered memory. When the quantity of data stored in the buffer memory is in excess of a predetermined level, the video signals of the next scanning line are regarded as being completely identical with those of the preceding scanning line. Morrin II, in U.S. Pat. No. 3,987,412 describes a data compression system using a boundary follower. This system contemplates raster scanning an image until a first black picture element is ascertained. The outer border of this image is encoded by a border follower which drives a cursor. The border follower records each black picture element as is is encountered as a series of discrete differential azimuths in a chain link code form. Johannesson in U.S. Pat. No. 4,087,788 describes a system in which data compression is achieved through analyzing the images and utilizing special encoding for geometrical shapes. Adachi, in U.S. Pat. No. 4,270,148, discloses a system based on the run length encoding technique for data compression while Kashioha et al, in U.S. Pat. No. 4,288,816, teaches repeatedly scanning the same image at different sampling points. Finally, Mitchell, in U.S. Pat. No. 4,355,306, teaches a system which encodes images by assigning variable length code words to fixed positions in a dynamic stack, utilizing vertical reference and run length encoding.
The on-the-fly data compression system described herein is an alternate method for data compression using a word representation by associative processing buffer and a content induced transaction overlap transmission protocol similar to that disclosed in commonly assigned U.S. Pat. No. 4,493,074 entitled "Content Induced Transaction Overlap Communication System," issued Jan. 8, 1985.